Is there a final word yet on whether upgrades will be available only from carriers, from HS if you open a new carrier account, or either way?

Seems there's still some uncertainty on this, but "only from carriers", or "from HS if you open a new carrier account" makes sense, I suppose.

If that's correct, it means that the only way to get an unlocked upgrade is with the carrier and hope they will unlock it after some minimum time period. (Not a guarantee with T-mobile, as they refused to unlock my 2nd and 3rd 270, in spite of the fact that my original unit was an unlocked HS.)